Endoluminal grafts have been used to repair blood vessels affected with any of a variety of lesions which can compromise circulation through the blood vessel to a portion of the body. The graft may be made of dacron, expanded polytetrafluoroethelyne (ePTFE), or a natural substitute such as a vein or artery taken from another portion of the body. Typically, the graft is held in place within a blood vessel by means of an expandable stent.
A variety of different stents have been used and proposed for this purpose. One stent, known as a Palmaz stent, has been used as a means for anchoring a graft within a blood vessel. The Palmaz stent is illustrated in FIGS. 1A and 1B of Palmaz U.S. Pat. No. 5,102,417. In this patent, the Palmaz stent is characterized as an "expandable intraluminal graft" The patent contains an extensive description of the prior art and the problems which the Palmaz stent was designed to overcome. U.S. Pat. No. 5,102,417 (the "Palmaz patent") and its parents are hereby incorporated by reference into this specification.
The basic Palmaz stent comprises a mesh-like tubular member which can be expanded from a first diameter to a second diameter. The stent may be expanded by means of a balloon catheter, the force applied by the balloon exceeding the elastic limit of the stent so that when the balloon is deflated, the stent remains in its expanded form. Since expansion of the stent can be closely controlled, if the stent is expanded into contact with the surface of a blood vessel, a graft positioned between the stent and blood vessel can be secured within the blood vessel.
As explained in the Palmaz patent, the Palmaz stent provides benefits in addition to the ability to anchor a graft at a desired location within a blood vessel. For example, the stent can be used by itself to prevent the recurrence of stenoses, and to prevent recoil of an elastic vascular stenosis. It is usable in critical vessels such as the left main coronary artery where the possibility of the intimal flap blocking blood flow limits the use of balloon dilatation procedures.